Milling and like machine for copying and reproducing



- Nov, 20, 1945. J. T. BOLAS 2,389,415?

MILLING AND LIKE MACHINE FOR COPYING AND REPRODUCING- Num 20, 1945. J. T. BOLAS f 2,339,407

MILLING AND `LKE MACHINE FOR COPYING AND REPRODUCING Filed sept. 15, 194s e shets-sheet 2 ya INEA/W lla/7W EMA? Nov. 2o, 1945.

J. T. BOLAS 2,359,407

MILLING AND LIKE MACHINE FOR COPYING AND REPRODUCING Filed Sept. 15, 1945 6 Sheets-Sheet 5 /F/Gg,

. I "30 //l\J 85 /54 Nov. 20, 1945. J. T. BOLAS 2,389,407

MILLING AND LIKE MACHINE FOR COPYING AND REPRODUCING Filed Sept. 13, 1943 6 Sheets-Sheet 4 vf/A/ 7T 30MB :mw/wo le;

Nov. 20, 1945.. J. T. BoLAs 2,389,407

MILLING AND LIKE MACHINE FOR COPYING AND REPRODUCING Filed Sept. 13, 1945 6 Sheets-Sheet 5 Nov. 20, 1945., .L T. BOLAS 2,389,407

MILLING AND LIKE MACHINE FOR COPYING AND REPRODUCING med sept. 1s, 194s s shets-sheet e Patented Nov. 20, 1945 MILLING AND LIKE MACHINE FOR COPYING AND REPRODUCING John Thomas Bolas, Bristol, England, assigner to The Bristol Aeroplane Company Limited, Bristol, England, a company of Great Britain Application September-13, 1943, Serial No..502,182 In Great Britain July 28, 1942 8 Claims. (Cl. S10-13.5)

'lhis invention relates to milling or like maclnnes of the kind comprising a cutter support and a work support, which cutter support is mounted for movement relatively to the work support along two substantially perpendicular paths, a pattern support*and a follower toco,- operate with a pattern on the pattern support, which follower is mounted for movement relatively to the pattern'support along two paths parallel to the aforesaid paths and is so interconnected with the cutter support that their compounded relative movements are similar, two reversible hydraulic motors arranged one to impart the said relative movement in either direction to the cutter support and the follower along one pair of parallel paths and the other along the `other pair of paths, and control means automatically operable to adjust the directionof operation of each motor in accordance with the configuration of a, pattern on the pattern support and the position of the follower relatively to that pattern. In such a machine the follower follows the outline of the pattern and constrains the cutter support to move in a corresponding manner.

In prior machines of this kind, the control.

operating as a feeding motor, the other is brought into action as a holding 'motor to feed the fol.l

\ lower towards, and hold it against, the pattern so that the actual path traced by the follower relatively to thepattern is compounded by the relative movements given to it by the two motors as restricted by the outlineof the pattern. The holding motor acts to hold the follower against the pattern to ensure that its outline is accurately followed but it will not do so .satisfactorily if the feeding motor is feeding the follower along a path inclined away from'the pattern at an angle in the order of 45 since the rate at which the holding motor feeds the follower towards the pattern may not be suincient to ensure that it does not leave the pattern. It has been proposed to supply motive fluid to the motor which is 4acting as the holding motor at a lower pressure than that at which it is supplied to the other or feeding motor sinceza lower pressure can be be less than the rate at which it is fed byfeeding This proposal would rangement the maximum rates at which the ltwo operating at the low rate to feed the followerl along the other path. away from the pattern,Y the resultant movement of the follower being thus v motor away from the pattern and the risk that the follower will leave the pattern is increased.

Accordingv to thepresent invention, a milling or like machine of the above kind is provided withmeans for supplying each motor with motive `fluid at substantially constant pressure and at Variable ratewhich means is adjusted by the control means to supply. fluid to each motor at the appropriate rateV for each position of the follower relatively to the pattern. With this armotors canmove the follower along itstwo paths relatively to the pattern are adjusted in. accordance with the position of the follower in such .manner that the follower is moved kat all times ytowards the pattern. Thus the follower would be moved over a portion of the pattern that is inclined at 45 to both its paths by one motor operating to feed the follower at the high rate along one path towards the pattern and the other directed towardsthe pattern. f

A milling or the like machine according to the invention is particularly suitable for cutting holes in the wall of a hollow body. Thus in sleeve valve internal combustion engines the valve sleeve is formed with a plurality of ports which can .be` .3', cut rapidly and to ahigh degree of accuracy by a milling machine constructed in accordancewith the present invention. According to' yet another feature of theinvention this is provided for by compounding the movement of the follower and 1;; cutter of an arcuate motion described about the centre of the cylindrical element and a linear motion parallel withthe long axis of the element.

A specific embodiment of the invention will now be described by way of example with refer- .ence to the accompanying drawings which illustrate a machinedesigned for the purpose of s1- multaneously cutting four ports in a valve sleeve for an internal combustionengine.

In the drawings- Figure 1 is a plan view of the lmachine showing its general arrangement;

Figure 2 is a sideA elevation of a cutter head forming part of the machine; p

Figure 3 is a plan .-view of the cutter head;

Figure 4 is a section on theline IV-IV of Figure 1 showing an outline` of one of the patterns and of the means associated with the follower for initiatingthe changes in the drectionand/or rate of ymovement of the follower as it traverses the pattern;V

Figures 5 and 6 are diagrammatic views of the means for bringing about the changes in movement of the follower;

Figure '7 is a section of a cutter head taken on the line 'I-l of Figure 3 Figureis asection on thel line 8-8-of Figure',and

Figure 9 is a section on the line 9-0 of Figure 5.

As shown in Figure l themachine generally comprises a table I which rcarries four cutter heads II each of which is capable of reciprocation on the circular slides I2. vThe sleeve I3 in which are to be cut ports I4 is clamped in position on table I0 so that it is centrally disposed about axis l5 and surroundingY the sleeve is a Y ring I6 having patterns I1 formed in the wallsY pressure uid passes by pipe 69 to the hydraulic motor the slide will be lowered. As is clear from Figure 7 the spindle 206 is mounted for rotation in the slide 23 so that when the latter is raised Vand lowered the spindle 20G, and hence the cutter I8 and follower 20, partakerof a similar movement. Y y

The drive from the motor I9 to the spindle 206 i is in no way affected by the vertical movements thereof (see Figure 7). The slides I2, ring I6` n and sleeve I3 are concentric. One cutter head I I anditsassociatedparts will now be described in detail. f i' The head II carriesa cutterI8 which is in driving engagement with a spindle 206V (Figure 7) that extends through the Vhead from the rear end thereof towards the axis I5. The head carries anelectric motor I0 `the spindle of which is provided witha gear 202` which forms'part of a gear train202, 203, 204 and 205, the latter being carried on the spindle 206. In this way the electric motor I5 transmits drive to the spindle 206 and hence to the cutter I8., 'Ihe spindle 206 passes centrallyvthr'ough the roller 20 which constitutes the follower referred to above.'V This particular disposition of followerfand cutter combined with the small extent which they protrude from the cutter head ensures that the cutter vand follower reproduce the outline of the pattern I'I without variations due to deflections of the cutter and follower.

When each cutter I8 is advanced into cutting relationship Vwith sleeve I3, follower moves inwardly over pattern Il; if thev follower is then moved around the periphery of thepattern to the cutter willprod-uce on therouter face of the sleeve a groove of similar outline to that of the, pattern. The path followed by the follower 20 and nected to'a pin V201 carried by a lug 208. YThe latter is secured t0 a portion 209 of the head II so that when the ram is reciprocated its movement is transmitted to the head Il through the agency described. The .horizontal movements imparted to the head II will beapplied to the cutter I8 and the follower 20 since these are carried 4by the head. It follows therefore that mog tor 2l will impart to the cutter and follower horizontal movements about theraxis I5. It is to be understood'that the motorZI is suitably carriedon the under face .of the table I0. 'Ihe vertical movements of the slide 23 are produced by a hydraulic motor 24 which is carried by the cutter head; The ram 2000i 'the hydraulic motor 24 is connected by rodH20I with the slide 23 so that when pressure duid isv admittedto the hydraulic motor ram 200 will reciprocate the slide 23 upwardly or downwardly in a vertical direction. Thus when pressure lfluidpasses by pipe 68 to motor 24 the slide will be raised and when which are imparted to the slide 23 since the motor andthe gear train between the motor and the spindle 206 are all carried by the slide 23 and are moved vertically therewith.

The hydraulic motors 2I and 24 are each supv plied with fluid under pressure (as will be more fully described hereinafter) by an associated variable delivery pump so that the rate of movement of the follower 20 and cutter I8 can be altered in both the horizontal and vertical directions by adjustingV the pump delivery. Y

Let it be assumed that the follower (and hence the cutter) is about to trace out the port outline I4 shown in Figure 4: the follower is in engagement with pattern I'I. and the common axis of follower and cutter coincides with point a. As the follower travels around the periphery of the pattern in an anti-clockwise direction the track which it describes is as follows:

(i) From `0L to b the horizontal hydraulic motor 2I is supplied by its pump at a righ rate of delivery and consequently the rate of movement of the follower in a horizontal direction is correspondingly high. During this movement the hydraulic motor 24 is supplied with fluid at a low rate of delivery so that the follower remains in contact against surface p and accuratelyy follows the pattern. v

(ii) From b to c the horizontal hydraulic motor 2I is supplied with iluid at a low rate of delivery so that the follower accurately follows the pattern round the bend and down face q. The vertical hydraulic motor 24 is supplied byits pump at a high rate of delivery so'vthat the rfollower moves downwardly ata correspondingly high rate.

(iii) From c to d the horizontal `motor 2| is supplied at a low rate so that the follower tends to move slowly in a directionlaway from face r but to ensure that the follower is kept in contact with the face the vertical motor 24 is supplied with fluid at a high rate so as to move the follower downwardly at la correspondingly high rate.

(iv) From d to e the hydraulic motor 2| is supplied at a high rate so that the follower moves rapidly along the surface whilst being maintained in contact with the face s by uid which is delivered at a low rate tothe Vertical motor 24 by its associatedpump.

(v) From e to ,f the horizontal hydraulic motor 2l urges the follower against face t whilst the Vertical motor 24 draws the follower along the face ata high rate of movement.v

(ci) From f to a the horizontal hydraulic motor 2l is urging the follower against surface u for whichvpurpose it is fed with fluid at a high rate of supply whilst the vertical motor 24 moves the follower along face u towards point a at a low rate of movement: this ensures that the follower is kept in contact with the face of the pattern.

It will have been appreciated that by suitably selecting the direction and rate of movement'of the follower in a horizontal and vertical direction it accurately follows the contour of the pattern, these factors being suitably preselected when a change in contour is immediately due to.

take place as the follower moves around the pattern.

The means for initiating these changes in direction and movement'is shown in Figures 4 andV switch rod 25 against stop 26 carried by table I'G` so that electric switch is closed, `The closing of this switch energisesone or moresolenoids (as will be more fully hereinafter described) which brings into operation the horizontal and/or vertical motors 2l and 24, the required direction and rate of movement inthe horizontal `and vertical directions of the follower Aand cutter during its movement along face p is produced. Similarly when follower and `cutter occupy position b the cutter head I I is in its extreme left-hand position in moving to which switch rod 21- hasengaged stop 28 (which is carriedby table Il!) and electric switch b is closed to select the feeds to the hydraulic motors 2|, 2-4 which willv result in the follower accurately following face q of the pattern. Whilst the follower is traversing face q the cutter head remains in the 'extreme lefthand position so that switch b remains closed. The follower/moves downwardly however' until it reaches point c whereupon .switch c is closed and the feeds to the hydraulic motors selected.' for the follower to traverse face 1' of the pattern. Closing of switch c' as described is effected by switch arm 29 which is carried by slide 23 and is zonsequently reciprocated in the vertical direction when the slide is operated to move the follower upwardly and downwardly; Now when the slide has reached the'- bottom of its travel and consequentlyI the follower has assumed position d switch d' is closed. This switch is in series withk switch d which is normally closed: accordingly when. switch d closes, the feeds from the pumps to the hydraulic motors are suitably selected forv the follower to move across face s of the pattern. The verticalV slide 23 in its lower extremity engages trigger arm 30 so that when the cutter head Il moves to the right arm 30 is displaced firstly to open. switch d and then when the head has reached a position in which the follower coincides with point e to close switch e'. This again selects the desired feeds to the hydraulic motors so that the'follower accurately traces the contour t; this involves an upward movement of the vertical slide which takes it out of engagement with arm 3G'. The latter is then spring urged to assume its normall `position whereupon switches d andV e are opened as switch d" is closed by the return springs of the switch. When the vertical slide has risen so that follower reaches point f the switch arm 29 has taken upa position to close switch f' thusr selecting the feeds to theY hydraulic motors which are required for the follower to move over part u of the pattern. This movement continues until .the follower reaches point a: advantage' being taken of the horizontalmovement of the cutter head entailed so that switch a is closed when the follower reaches this point. To ensure that the follower and cutter do not commence their travel along face p before the follower has completed its travel along face u to its highest position switch a is provided inA serieswith switch;

a so that the horizontaland vertical hydraulic motors are not fed with uid toy direct the follower alongfacefp until switch arm 29 has taken up" a fpositi'onztoV close switch a 'Toensure that .switch arm 29 only engages switchflcfin its downward travel and switch f during itsiupward travel the switch arm carries a-selectoridevice generally indicated at2'l'l (Figure 19S). The latter comprises a channel member 2128i which is carried by the arm 29 and a contactpiece .31 mounted therein. The contact piecey 311 is maintained in frictional engagement with the .member 2 I8 by `means of a plate 22E] between which and the contact piece3l there is disposed acfriction plate 2I9. The friction plate 2|'9 and the plate 2v2-0 are' pressed into engagement with the contact piece 3| andthe latter into engagement with the member 218 by bolts 22| which pass'through a cover plate carried by the member 2l8. The contact piece3l engages stationary pins 32 and 33 respectively during the upward-and` downward travel of the member 2l8 when the arm v29 isv moved in the corresponding directions. `Thus as the arm approaches the upper limit of .its travel the Contact piece 3l engages pin 32 and is moved to the' left andV in its downward'. travel it engages pin 33 and is urged tothe right. The contact piece 3l is frictionally held in the member 2l8 in such a manner as to enable the pins 32 and 33 to move the contact piece yas indicated;y However, this frictional effectis of sufficient magnitude to ensure that when the contact piece 3i is brought into'engagement with the switches c and the latter are incapableof moving the contact piece relatively to the member 218" since the springs of these switches are not sufficiently strong for'thus purpose` As a consequence when the arm approaches the upper limit of its travel the contact-piece engages pin 32 and is moved to the left so that in` its'subsequent downward movement it closes switchc and clears switch f'. Having passed switch f', `contact-piece 3l engages'rpin 33and is urged to the right so that in the'subsequentlupward movement of the arm V29 switch f isfclosed and switch c remains open.

It will have been noted that when switches a' to V are closed they are immediately opened again by their associated springs which are respectively'indicated at2l0 to 2HE with the exceptionof switch b, the reason being that if the vsolenoids associated with any one switch are4 maintained energised the next succeeding switch may energise solenoids which conflict in their effect with thosethat have been maintained energised. This circumstance'does not arise in connection with switch b.

Turning now to' Figures-5 and 6: the train of events following the' closing of the switches will now bedescribed.v Broadly' `the effect of closing any one` ofthe switches is to energise one or more solenoids,`iea'ch 0f which either adjusts a valve controlling vthe Yflow of pressure air to a pneumatic motor,` which` in turn adjusts a hydraulic valve tofdetermine-the Idirectionof feedto the horizontal or vertical cylinder, oralternately adjusts the delivery of the feedf pump. So as clearly'to distinguish'between the electric circuit, the pneumatic pipe lines and the khydraulic pipe lines in the drawings the first is sh'ownas a thin single line, the second as a thick singleline and the third as a thin double line.

Figurey 5 shows the electrical 'switches a'f and the horizontal and kvertical hydraulic motors 2l, 24 already described: the electrical connections leading from the switches to the solenoids of Figure 6 are also shown.

Referring now to Figure 6: a constant `delivery pump 34 supplies oil under pressure to the varia'- ble delivery pumps 35, 35a so as to `maintain these pumps flooded whether they Vbe delivering iiuid or not. Fluid under pressure from pump35 passes toth'e horizontal hydraulic motor 2| (Figure by way of valve 36. The latter comprises three spaced piston elements 31, which are cou'- pled Atogether tov form a unit, longitudinalv adjustment of which enables the -fluid vowing from pump into pipe 38 .to be directed into-,either pipe 39 or 40. Th'e arrangement is that if the piston unit 31 is in its left-hand positions (asshown in Figure 6) iiuid is pumped along pipe 38, through valve 36, pipe 39 to the left-hand side of the hydraulic motor 2| to move the cutter head from left to right. Simultaneously uid is forced out of the motor 2| th'rough pipe 40, valve 36 and drain pipe 4|. If the pistons are in their righthand position iluid is' pumped through pipe v38,u valve 36, pipe to motor 2 I, and the cutter head moves from right to left. 'Simultaneously fluid drains Lfrom the motor by way` 0f. pipe 39, valve 36, and drain pipe 42. l

The hydraulic valve 36 is actuated by a pneu` matic motor 43. 'Ihe latter comprises a pair of pistons 44, 45, which are connected with the piston unit 31 by links 46. When air under pressure acts on piston 44, valve 36 is set to permitpressure fluid to reach motor 2| by pipe 39, similarly when air under pressure is admitted to piston valve 36 is set to permit pressure fluidlto ilow along pipe 40 to motor 2|. The admissionof pressure air to pistons 44, 45 is controlled by valve 55 which comprises th'ree spaced and coupled pistons 41 the are connected to one or more of the switches.

a'-f' already referred to. Thus in the position shown in Figure 6, solenoid 54 has been-energised, the pneumatic piston unit 41 isin its right-hand position and air under pressure passes from pipe 48 through valve 55, and duct49 to piston 44 to actuate the hydraulic valve 36 as described: at the same time air in the cylinder of piston 45 escapes by valve 55 and duct 52.

A similar arrangement ofsolenoids, pneumatic valve and motor and hydraulic valve is associated withvertical hydraulic motor 24 and variable delivery pump 35a. Hence solenoids 56, 51 actuate the pneumatic piston unit 58 of valve `59 to permit pressure air from pipe 60 to pass -to piston 6| or 62 of pneumatic motor' 63, said .pistons being re spectively `coupled to the hydraulic pston'unit 64 of valve 65L by links 66 so that pressure'fuid from the pump 35a enters valve 65 by pipetlV and passes by pipe68 or 69`to Vthe vertical'hydraulic motork 24. Asin the corresponding unit associated with the horizontal hydraulic vmotor. 2'|,

escapeducts'10, 1|Y are. respectively ,associatedY with pistons 6|, 62 of the-'pneumatic motor' and drain pipesf212, '213 respectively Withthehy-f draulic ,piston unit 64.

'I'he hydraulic and vertical motors 2| Vand 24 are supplied with pressure iluid at either /of two rates so that the motors produce a corresponding rate of movement of the follower and cutter. The rate of feed in the horizontaldirection is selected by the switches a'f' closingV the circuits Ato solenoids 13 or 1.4,todisp1ace the piston aesofior unit 15 of valve 16 to the left or right and permit pressure-air from line 11 to pass to cylinders18 or 19 respectively by way of `pipes 80,.-8l. When pressure air enters cylinder 18 piston rod 82 displaces lever 83 to its maximum extent'and the variable deliverypump 35 delivers .fluid -at a high rate with consequent fast movement of the head in the horizontal direction whilst if pressure rair is supplied tothe cylinder 1,9 piston rod 84 displaces thelever 83to its minimum operating extent and the'pump delivers at a low rate: the cutter head then moves slowly. The lever 83 is spring urged against the piston rods. Air from the inert cylinders escapes through pipe or 8|, valve 16 and pipes 86 or 81 respectively. In the same way the rate of feed inathe vertical direction is determined by switches a'-f closing the circuit tosolenoids 88, 89r associated with the piston unit of valve 9|' ,which regulates the -ad' mission of pressure air from pipe 92 Lto pipes 93 or94 and thence to the cylinders'95, ,96: -The piston rod 91 of cylinder 95 displaces lever arm 98. ofthe variable delivery Vpump 35a toprovide the high rate of delivery and-consequently fast movement in the ver-tical direction; the piston rod 99 of` cylinder 35 displaces arm' 96 'toensure lowrate ofdelivery from pump 35a. Air from the inert cylinder escapes by pipe 93 or'94, valve 9| and pipes |00, |0| respectively.. The means just described determines the rate at which .the

cutter will'move in each-,direction if it is not` constrainedI by the Ypattern which will, however, prevent, or slow down, the movement in one or the other direction so that the'associated motor will not take in uidor willrdo so moreslowly than it is delivered by the associated pump. The excess fluid is deliveredto drain through relief valves |36 and |31, connected-to the ydelivery pipes 38 and 61 of the'pumps`35 and 35a, and drain pipes |38 and I39. The relief'valves also limit theipressure at which the fluid 'is' delivered Vso thatit is delivered at'substantially constant pressure at the full loadk onk the motors.

,It will be noted from'Figure that the air sup ply to pipe 48 (which is lthe 'supply for regulating the direction and rate of movementfof' the follower and cutter in athorizontal direction) and pipes 60 and 92v (which is'the supply regulating direction'and rate of feed inv a vertical direction) passes through `valve |02.-" This valve comprises a piston unit |03 which is actuated by solenoids |04, .|05 energization of solenoid- |04 sets valve |02 to permit pressure air frornvthe main` supply line |06 to pass to the valves v55, 59,.16and 9| '.whilst energisationV oi solenoid |05 sets -valve |02 -to prevent admission of airto the valve and simultaneously, to enable the air in these valves to escape to atmosphere by'pipes 48, 68,- 92, valve |02 and duct. |01. i The apparatus describedso far hasV been concerned with impartingrmovements in a vertical and horizontal direction to the followerand cutter so =thatthe shape of the pattern isaccurately reproduced. It is necessary to provide means for advancing the cutter towardsthe work, and for increasing the depth of thecutas theA machining operation proceeds; it is` also highly desirableto provide Vavfsingle starting .control for the four cutter heads so that they simultaneously commence work vand to provide individual means associated with" each head to'operate Asolenoid |05V and valve |02 so that immediatelya 'port has been formed in sleeve I3 the tracing'operation of the follows that although the four vcutter heads start their cutting operations at the same time'the shapes of the valve ports being dilerent one may nish before the other.

lThe vertical slide 23 is carried by the cutter head I| through the intermediary of va horizontal slide |08 (Figure 3) which is capable of being advanced to bring the cutter .I8 against sleeve vI3. Slide |08 is advanced by two agents against the action of a spring 228 (Figure. 7) which at one end abuts the member 203 of the head and the other end of which abuts a'plate 229'.v The latter is secured to a plate 230 which is bol-ted to each of the slides |28 between which the slide 23 is carried. As a consequence when theislide |08 is moved towards the axis .l5 by either of said two agents the. Spring 2,28` is compressed and tends .to` urge the slide Hi8 back to its initial position. Of the two agents referred to Vone is .provided to advance 4the cutter up tothe and from these cylinders to drain (for-convenience only one such cylinder is shown in Figure 6). The piston rods |.I3 of .cylinders l engage a cross-member 4 (Figures l, 2 and 3) secured ,to the slide |08 by bolts 23|, so that when the handle 2214 of :control |09 .ispushed inwardly valve is set t0. allow-pressgure fluid from pump A34 to `pass to the infeed cylinders whereupon piston rods ll 3Y advance Ito.e,1rlgage.cross-mernber ||l| and` move slide |08 and cutter |.8 towards sleeve VI3. Y

The second agent which is provided to advance lthe cutter is an vinfeed cam |;5 which is carried by the cutter head and `which is driven (Figuresz, 3, 6 and B) through bevel gears lIIS, shaft ||"I and either pinion I I8 or pinions I L9, |20- from `rack |2| when the vertical slide 2.3 Whichoarr-ies the rack moves upwardly land downwardly respectively. Pinions liand ||9.each incorporate a pawl and ratchet free wheel device 225, l2.26 respectively so that inthe upward movement of vertical slide 23 the drive from Vrack `|2| is'transmitted to cam ||5 by gears 8, |6 whilst .pinions ||9, |20 are driven idly since the pa-wl vand ratchet device 226 is then designed to free wheel, and in the downward movement the drive is transmittedby gears |20, H9, IIB whilst pinion ||8 is driven idly since the paw] and ratchet device 225 is then designed to free wheel. The cam is thus always rotated in an anti-clockwise direction (see Figure) each time the .vertical slide is operated and, engaging with a roller |22 carried by a pin 221 which is threaded into .slide |113 advances the latter. and the cutter as it rotates.

The apparatus is designed so that-theportistcompletely cut when the follower has .traced around rthe pattern three times during which time it is necessary to advance the cutter from the initial to the final cut. This requirement is metby ensuring that the cam .I |'5 rotates once duringthe three circuits of the pattern described by the follower the number of times the follower traces around the ypattern to complete the cutting operation is determinedby the materialof the sleeve I3, its wall thickness, the cutting speed of the cutter I8 and the surface finish which is required for the wallof therports lll. The machine being described has been designed withthese factors in mind and the number of tracing movements referred towasselectedto ensure accuracy and good nish ,for eachport opening. When other con- .sderations prevail the number of tracing move- .passing U Sbasihe.- slide |08 Yis Shrine returned .to move .the cutter/...t8 away from the sleeve |3,v and consequentlythe roller |22 towards-the cam. 4

vActuationof the infeed cylinders I IVIv as described `aclvancr-:s `cross-ineinber ||1| and hence 'slide |08 suicientlyfforthe.roller |22 to be lifted Out YAof step H50 so that thereafter on the first vertical movement of slide 23 the cam I l5 will be rotated as described aboveto bring part of the cam lying between |,|5a-`. 5b into engagement withthe rollerem. The functionof the irleed cylindersisfullled when they brine cutter. |8 up tosleeve Itand rai-se roller |22 out of step ||5c as indicated. etant' timeafter the cutting 011eration has .been commenced (that is afterslide 23 has been moved vertically to bring cam H5 into engagement with-roller |22 to perform the infeed movement of-thecuttsr la) the control itemay be returned to its noni-operative position.` V.This

will not. result in. `an .interruption of the cutting operation but only in the-cylinders |.l beine connected to irai-nbr pipe I l2, valve Il@ and ppelt ashereinafter explained. .Y Y A The roller |22 engages a ylever |23 Whichis pvotally carried by the cutter head sov thatas the slide IDB .is advancedby the inieed cylinders IH and the cam ||5 :the lever lis continuously displaced by the roller in one direction: upon the rcllerdroppins nwstep H50 (theinfeed cylinders having previouslybeenfdranedso that slide |708 -Call be springY v,returrifri toits full extent) the lever |23 isreturned by Spring v2.34V toits initial position. This lever engages a switch rod |24 carrying unen an imma-tins block a contact niece 25,.said rodl 2li-being reciprocated as theglever is displaced `when the cutter is advanced and .reF

turned as above described. CQ-Operatins with Y contactpiece er@ three contacts liZi, |21 and |28 the rst-,of which -Whenii .engaged by |25 clcsesaoircuit `wlfichencruises solenoid m5 to .close valve W2 and thus-cut-cfithe pressure air Supply t0 the Various pneumatic valves `and motors-so that theelectricepneumatic-hydraulic apparatus is rendered inoperative the second |21?) energises solenoid |194 to .open valve V|012 and thus brille saidapparatusintooperation, andthe third (|23) energises solenoid |29 thereby todisplace thepiston unit |33 cf pneumatic valve IBI to permit pressure air ripe line `lts to pass ty branched eine 1.5.2 to pneumatic motors |33 and simultaneously return control |09 to its fo pcsition=and thereby nlacevalve :lle-0 so that Pressure huid-drains fromfthe infeed cylinders through Adrain:pipe 13A. The piston unit |30 is returned by spring |35 to a. position to cut-ort pressure airfrom pneumatic motor |33, whenthe contact niece ltpassesbeycnd the .Contact |28.

When :the infeed cylinders l advance the .cutter to the .cutting position, lever |23 `moves switch rod '|24 to bringfcontacts'l25, v|21 into engagement to energise solenoid |04 thereby bringing the apparatus into operationgand cam continuesthe displacement ofV switch rod v|24 until contactsv |25, |28 engageand solenoid |29 is energised with the effects described in the preceding paragraph. Whenthe cutter has traced around the pattern three timesland the'cutter has completed its cutting 4operation and has returned to point a (Figure 4) the rollerdrops into step I5c, the switch rod |24.is spring-moved to bringcontacts |25-, v|26 into engagement to energise solenoid |05 and thereby stop the apparatus.

The operationof the machine will now be described itbeing understood that the master control |09 simultaneously brings allV four cutter heads into cutting operations but that each head then performs the cutting operation independently.V Accordingly -the description will commence with the actuationof the master control |09 simultaneously to start the; cutting operation in the four cutter heads and will then `be concerned with the sequence of operations entailed in'cuttin'g one of the four ports, namely that shown in Figurefl'.y i v The generalvstate of the mechanism is vthat the follower and lcutteroccupy position a, switch a' is therefore closed, but in completing the last of the preceding sequence of operations contacts |25, |26 were engaged thereby energising solenoid |05 and adjusting valve |02 to render the apparatus inoperativeraccordingly switch a lbeing closed has no effect. The infeed cylinders II have been drained permitting slide |08 to 'be spring-returnedto its retracted'position and cutter I8 to be withdrawn from its cutting position: roller |22 is engaging step I|5c and accordingly switch arm |24 is in its outer position with contact |25 to the left of contact|26. The handle 224 of master control |09 is in its olf position (as shown in Figure- 6) Y so that valve ||0 is set to preventfilow of pressure fluid from pump 34 and pipe |40 to pipe II2 and hence to the'infeed cylinders III. Y I

Pumps 34, V3.5,y 35a are delivering uid but as thelast operation-performed Vby the hydraulic motors 2|, 24ewasf that of moving the follower along face u of the pattern, valves 36,v 65 (Figure 6) Y remain set in a position to enable this operation still to be performed.v vrThe-follower is therefore pressed inwardly to the corner formed between faces p andV u, and switch arm 29 will be in its highest position so that-iswitch-af is closed. As the uid being circulated by pumps 35, 35a cannot drive the hydraulic motors 2|,` 24 their action being merely to press the follower'against faces p and u of the pattern I1 the uid under pressure is delivered to drain through relief valves |36, |31 and drain pipes |38, |39 respectively. Similarly the fluid under pressure from pump 34 passes to the closed valve I|0 by pipe |40 and is delivered to drain by way of relief valve I4| and drain pipe |42. v Y

From the disposition of the various parts referred to above, the cutter heads I| are simultaneously brought into operation upon the operator pushing thehandle 224 of the'master control |09 inwardly to set valve |0 so-that pressure uid from pump-34 passes byvpipe |40 to the valve and therefrom to each-pair of infeedi cyl'- inders associated with each cutter head Iby a pipe I|2 leading to each such cylinder, whereby piston rod ||3 is advanced, engages bar II4, and moves slide |08 forward so that cutter I8 is .brought up to sleeve I3. Thecutter is nowin a position ready tocommence the cutting operation which will result in the formation of port I4, motor I9 having previously been started to drive the cutter I8. Simultaneously withthe advance of cutter I8 roller |22 carriedby slide-| 08 is raised clear of step ||5c. f

In performing the operation of advancing slide |08 lever |23 is displaced to move switch rod |24 downwardly so that contact |25 is moved to engage contact |21, I

Engagement of contacts 125, |21 Vcompletesv the circuit from the source of electrical supply |43 (in the present instance'a transformer) to solenoid |04 by conductors |44, |45, |46 and the earth return |41 so that-the piston unit |03 of valve |02 takes up the position shown in Figure 6. Pressure air from the main supply line |06 is then free to pass to pneumatic valve 9| by pipe 92, to valve 59 by pipe 60, to valve 55 .by pipe 48, and to v-alve 16 by pipe 11; 'the electric-pneumatic-hydraulic apparatus is accordingly brought into operation. Y Y

As already stated electric switches a' and a are closed so that a circuit from the transformer |43 by conductors V|44, |45, solenoid 53, conductors |48, switch a', conductor |49, switch a" to the earth return conductor`|50 is completed and solenoid 53 is energised. The piston unit 41 of valve 55 assumes its left-hand position so that pressure air from pipe 48 flows through duct 50 and acting on piston 45 of pneumatic motor 43 moves piston unit 31 of valve 36 to the righthand position. Simultaneously air is expelled through duct 49 by piston 44 and `escapes through valve 55 and escape pipe 5|.v Movement of the hydraulic valve 36 permits pressure fluid from pipe38 to pass along pipe 40 to hydraulic motor 2| which thereupon operates to move the cutter head over slides |2 from right to left. Fluid in the hydraulic motor 2| is simultaneously expelled through pipe 39, valve 36, and escape pipe 42. It is necessary that the follower move over face p of pattern |'1 in the direction indicated, at a high rate of movement andthat simultaneously thev vertical motor is supplied by pump 35a with Vpressureuid at the low rate of delivery so that vertical slide 23 is directed upwardly and follower 20 engages face p of the pattern.v This vertical movement has already been selected by switch b' when the follower was at point b as will Aappear hereinafter and accordingly no change in theoperation of the vertical motor 2| is required at point a.

Y The horizontal motor 2| moves the cutter head .II from its right-hand position towards the left (Figure 3) Ywhen this motion commences, switch rod 25 disengages stop 26 and switch a is opened thereby breaking the circuit to solenoid 53. As the head approaches its left-hand position and the follower reaches point b, switch rod 21 engages stop 28 and closes switch b', whereupon the circuit from transformer |43 vby conductors 44, |45, solenoid 56, conductor v|50 and earth return |5I is completed: solenoid v56 isenergised and pistonunit 58 of'valve 59 isdisplaced to permit pressure-air from pipe 60 to pass to piston 62 which is thereupon displaced to move piston unit 64 'of hydraulic valve 65 to the right and permit pressure fluid from pipe 61 and pump 35a to enter hydraulic motor 24 by pipe 69, whereupon the motor operates to move slide 23 downwardly with simultaneous draining of fluid from the motor by pipe 68, valve 65, anddrain pipe 13. This will Adirectthe follower20 downwardly along face .q.. .A highvrat'e of feed in this direction should be provided: this is also effected .byswitch b' closing a circuit incorporating transformer |43, conductors |44, |52, solenoid 89, conductor |153, switch b and earth return Solenoid 89 is thus energised, piston unit 90 is-drawn'towards the solenoidA and pressure air from pipe 92 passes by pipe 93, to cylinder 95 to displace piston rod '91and lever 98 to setpump 35a to deliver to the hydraulicvmotor- 24 at the higher rate. Simultaneously air escapes from cylinder 96 by pipe 94; valveA 9| and escape pipe |0-|. The direction of movement of the follower inthe horizontal direction as it traverses face q of the pattern is to be maintained the same as for face p; as however itis only required to press the follower against facer q` the rate of fluid supply to motor 2| is to bechanged from the higher to the lower value, Accordingly switch b' also completes a third circuit including transformer |43, conductors |44, |415, solenoid-13, conductor |54, switch b and earthA return |5|: solenoid 13 is thereby energised and piston unit moves Vtoward the solenoid to permit air under pressure from pipe 1'1 to pass 4through valve 16 to pipe 8| and cylinder 19to displace piston rod 84 and lever 83 to select the low'rate of Vfeed from the pump 35a. Atethe same time air escapes from cylinder 18 bypipe 80, valve 16, andfescape pipe 86.

VSlide 23 is moved downwardly and the follower `traverses face-q, the cutter head being maintained in its left-hand position by hydraulic motor 2| Vand accordingly switch b remains closed.

As'slide 23 moves downwardly it carries rack |2| with it and drives cam ||5 through gear ||8,

shaft ||1, and bevel gears ||6 so that the cam is energised and draws piston unit 41 of valve 55 towards it and pressure air from pipe 48 is passed by duct 49 to piston 44 which it displaces to move the piston unit 31 of hydraulic valve 36 to the left.- This permits the fluid which is being supplied by pump 35 at a low rate of feed to pass from pipe '38 to pipe 39 and hydraulic motor 2| which thereupon moves the cutter head away from stop 28 towards the right. y

The head moves toward the right and simultaneously slide 23 is moved downwardly at a high rate of movement so that the follower remains in contact with face r of pattern |1. When vthe follower leaves point c in its movement along face r the horizontal movement enables switch b to open and the downward vertical movement permits switch cto open. f Further downward movement of switch rod 29 carries contact 'piece 3| past switch contact f' without however closing the circuit incorporating this switch. As contact piece 3| passes pin 33it engages therewith Vand the contact piece is moved to the rightsov that Aon thesubsequent up- 'ward movement of rod` 29 switch f only will be Closed.. i v

,When the lfollower' and cutter reach'theirlcwest extremity `(which occurs when the follower reaches point d-)` 'switch d' is closed (and as ala circuit including transformer |'43,conductors |44,' |45, solenoid 88, conductors |56, |51switch d", conductorfl'58,'switch d and earth return |50 is completed to energise solenoid 88 .whereupon piston unit 90 of valve 9| moves towards the solenoid and pressure air passes from pipe 92 `throughvalve 9| to pipe-94 and cylinder96 to-set pump 35a for the lowfrateof fluid delivery. At the same time 'air escapes from cylinder 95 by pipe 93, valve 9|, and-escape--pipe |001; 1When switch d' -isclosed it also completes a circuit containing transformer |43,conductors |44,' |52,-

solenoid 14, conductor |51, switch d", conductor |58, switch df vand earth return conductor |50.

This effects energisation of solenoid 14 with consequent vmovement `of piston `unit 15 of valve 16 towards the solenoid. Pressure air from pipe 11 passes throughthe valve to pipe and cylinder 18, which results in the highrate of feed-to hydraulic motor 2|. When valve 16 is set as described it enables air in cylinder 19 to escape by pipes 8| and 86. Follower 20 will consequently move across face s at a high rate of movement in the horizontal direction and with a low rate of feed to vertical motor 24 to keep the follower against thisfface. I

A s the cutter head |'commences to move to the right, the verticalslideY 23 which isat its lowest extremity engages arm 30 and bringsit initially into engagement with switch rod 89 and then moves the latterto'open switch d. As the sleeve continues its movement arm 30 continues to displace switch rod towards the left `until when the follower 20 has reached position e, the switch rod has been so 'displaced that switch e closes. This brings into operation three circuits, one comprising transformer |43, conductors |44, |52, solenoid 51, conductor, |59, switch e and earth return |60,v the second 'comprising transformer |43, conductors |44, |52, solenoidvSS, conductors |53, |6|, switch E2 and earth return |60, whilst the third comprises transformer |43, conductors |44, |45, solenoid 13, conductor |54,switch e' and earth return |60. It will be noted that earth return |60 is associated only 'with switch e" and not with switch d The eil'ect of energising solenoid 69 is to draw piston unit 90 towards the solenoid and permit pressure air to pass from pipe 92 by way of valve 9| to pipe 93 andA cylinder 95 so as to select the high rate of fluid supply by pump 35a to hydraulic motor 24, whilst the effect of energising solenoid 51 is to draw piston unit 58 of valve 59 towards the solenoid thereby permitting pressure air to pass to piston 6| to displace it and piston unit 64 of hydraulic valve 65 whereby fluid from pump 35a ows by pipes 61, 68 to motor 24 which thereupon operates to raise slide 23 and cutter |8 carried thereby. The effect of energising solenoid 13 is to displace piston unit-15 to the left to per mit pressure air from pipe 11 to pass by way 4of `pipe 81| to cylinder 19 whereupon the slow rate of fluid delivery is selected for pump 35. Simultaneously with the operation of the hydraulic motors and rate-selector cylinders as above described, escape of air and drainage of hydraulic fluid is reilected through the various valves as already described hereinbefore.

As slide 23 moves upwardly it disengages arm 30 which moves to its normal position away from 'switch rod 85, switch e is spring-opened and switch d" closed. Due to the upward movement of sleeve 23, switch arm 29 ascends and switch ready stated switch d isnormally closed) sothat d opens so that .no-train of eventsfollows; this closing of switch d. p

, When the followervhasmoved over facetan'd reached point switch if', is closed completing two circuitsone including transformer` |43, coni ductors |44, |45, solenoid-88, conductors |56, |5'|, |62, switch f' and earth return |50, the, other including transformer` |44; |52,: solenoid"|4, conductors |5 |62,=switch J" and earth return |59.

By thus energising solenoid 88,' piston unitil of valve 9| is Vdrawnytowards the solenoid and permits pressure air to reach cylinder 95 by pipe 94 whereby a slowrate of duid feed to motor 24 results. Air is simultaneously drained from cylinder 95 as has already been described. Solenoid 14 is energised to set valve llto allow pressure air to pass to cylinder '18- thereby selecting the high rate of feed to hydraulic motor 2|. The follower traverses-face, u of the pattern land von reaching pointa switch a is closed with the results already described.

After switch l" is closed the further upward movement of switch rod 29 carries Vcontact piece 3| past switch contact cwithout however closing the circuit incorporating this switch. As contact piece 3| Apasses pin 32 it engages therewith and the contact piece is moved to the left so that on the subsequent downward movement of rod 29 switch c only will be closed. Y y

During the upward movementof slide 23 as the follower traverses thel pattern from, position eto a rack |2I drives cam I5fthrough gears |20, IIS, shaft II'| and bevel gears |I6 sothat rotation of the cam advances cutter I8 and increases the depth of cut. however the free-wheel device incorporated in this gear enablesthe gear to rotatev idly.

The sequence of operations outlined above is repeated until the follower has traversed the pattern three timesand returned to position a. The

cutting operation is then complete, the port having been formed in sleeve I3. n

As the follower moves along, face u in its last circuit around the pattern, cam I I5 is advancing roller |22 and hence cutter I 8 to the limit of their travel. Switch rod .|24 is therefore approaching its lowest extremity and in so doing brings contacts |25, |28 into engagement whereby a circuit including transformer 4|43, conductor- |44, solenoid |29, conductor |63, contacts |25, |28 and earth return |41 is confipleted.v Solenoid |29 on being thus energised draws piston |30 of valve |3| towards the right against the pressure of spring |35 to permit pressurel air from.main pipe line I U6 to reach pneumatic motor |33 by'wa'y of ducts |32. Valve IIB is consequently moved to. 'the right to place thehandle'224 of themaster control H39 in the off position and to permit fluid to drain from infeed cylinders l'by'way of pipe ||2, valve H and drain pipe |34. Although vthe infeed cylinders are thus drained cam `I l maintains the cutter forward lin its cutting position.

When follower has reached position aand the cutting operation has been completedroller |22 has passed point I|5b of cam- H5. ASlide '|08 is then spring urged to 'retract the cutter `fromits working position. Roller |221 thereupon-drops into step ||5c and as a Vconsequence switch rod |24 is spring returned upwardly and contactsV .|25, I 26 engage. The circuit incorporating transformer |43, connectors |44, |45, solenoid |05, conductor |64contacts |25, IZB-fand earthreturn |4I is thereby completed.' Solenoid |ll5 ,when thus energised draws vpiston unit yH33 of valve |02 towards it and thereby cuts oil the `'supply Rack [2| also` drives gear ||8,.

of lpressure fair from main pipe |06 ,to pipes `,48, Bill, 'I 'Iv and 92 thus renderingithe electric-pneumatic-hydraulic apparatus inoperative.

' In the event Vthat Ythe operator wishes to stop `any oneof thefour cutter heads ,an emergency stop switch I B5 (Figure 6 )is provided in the eleccompressed air to the pneumatic valves andmolet ItY will be appreciated that the switches a-f are selected to close at lsuch times that it will be ensured the follower is always maintained in contact with the pattern. Asvthe outline of the port or otherhole whichis to be out varies so will 4the disposition -of the switches relative to the peripheral path of the follower. Although in the above description a total of six switches was referred toit .is to be understood that a greater or in certain limited Acases a lesser number may be provided.` Y y The machineforming the basis of the invention is also capable of being used forrproducing irregular shapes in plane bodies for instance in forming the scallops commonly found around the periphery of the articulated-rod carrier of a radial engine vconnecting-rod. The apparatus. may be also used for the accurate productionof positive cams, in which case the cutter forms a cam groove in the cam plate the cutter being advanced towards the plate as it moves along the groove until the required depth of groove is produced whereupon the cutter is retracted from the cutting position.

I claim: Y

l.r A milling or like machine comprising a cutter support and` a work support, which Vcutter support is mounted for movement relatively to the work support along two substantially perpendicular paths, a pattern support and a follower to co-operate with a pattern on the pattern support, which follower is mounted for movement relatively to the pattern support along two paths parallel to the aforesaid paths and lis so interconnected with the cutter support that .their compounded relative `movements are similar, V'two reversible hydraulic motors arranged one to irnpart the said relative movement to thecutter support and the follower along one pair of parallel paths and the other along the other pair of paths, a separate variable delivery pump and relief valve for supplying each motor with motive fluid 4at constant pressure, means for independentl'yvarying the delivery of each pump, and-conltrol, means automatically operable to adjust the direction of operation of each motor and the rate .at which motive fluid is supplied to it inVv accord- V1, comprising a separate pneumatic motorfor adjusting each variable-delivery, pump, and 4'a separate pneumatic valve for each said pneumatic motor which valves are actuated by the electrical means.

4. A milling or like machine according to claim 1, wherein the follower is constituted by a roller through the centre of which a milling cutter or its driving spindle passes.

5. A milling or like machine according to claim 1, wherein the cutter support is movable towards the work support, and means is provided for automatically advancing the cutter support towards the work support when the follower has completed its travel over a pattern in the pattern support to increase the depth of cut.

6. A milling or the machine according to claim 8 wherein the machine is brought into operation by a master control, said control opening a hydraulic Valve to allow fluid to pass to a hydraulic motor which is provided for the purpose of advancing the cutter to the working position at a high rate of movement and simultaneously closing an electric switch associated with a solenoid which is adapted to open a valve and permit air to pass to said pneumatic valves.

'7. A milling or like machine according to claim 1 in which the cutter cuts a hole in a hollow cylindrical member and in which the motion of the follower and cutter is compounded of an arcuate motion described about the centre of the cylinder and a linear motion parallel with the long axis of the cylinder.

8. A milling or like machine comprising a cutter support and a work support, which cutter support is mounted for movement relatively to the work support along two substantially perpendicular paths, a pattern support and a follower to cooperate with a pattern on the pattern support, which follower is mounted for movement relative to the pattern support along two paths parallel to the aforesaid paths and is so interconnected with the cuttersupport that their compounded relative movements are similar, two reversible hydraulic motors arranged one to impart the said relative movement to the cutter support and the follower along one pair of parallel paths and the other along the other pair of paths, a separate variable delivery pump and relief valve for supplying each motor with motive fluid at constant pressure', means for independently varying the delivery of each pump, arid control means automatically operable to adjust the direction of operation of each motor and the rate at which motive fluid is supplied to it in accordance with the configuration of a pattern on the pattern support and the position of the follower relatively to that pattern, a sepa.- rate pneumatic motor for adjusting each variable pump, a separate pneumatic valve for each said pneumatic motors, said valves actuated by electrical means, and a plurality of electrical switches, said switches being brought successively into operation as the follower travels around a pattern on the pattern support, each of said switches being connected with solenoids which actuate said pneumatic valves.

JOI-IN THOMAS BOLAS. 

